Health Topics for Infectious Diseases

Department of Internal Medicine: Infectious Diseases

Department of Internal Medicine: Travel Medicine

Group A streptococcus

What is group A Streptococcus? Group A Streptococcus is a type of bacteria found most often in the throat and on the skin. When present, there may be no symptoms of disease or it may cause infections that range from mild to life- threatening.

The majority of group A Streptococcus infections are relatively mild illnesses, such as strep throat or impetigo. Occasionally, Group A bacteria can reach parts of the body where bacteria are not usually found, such as the blood, deep muscle and fat tissue, or the lungs. When this occurs, serious infections can result, such as necrotizing fasciitis and streptococcal toxic shock syndrome.

Necrotizing fasciitis (sometimes described by the media as "the flesh-eating bacteria") is a destructive infection of muscle and fat tissue. Approximately 20 percent of patients with this infection die. Streptococcal toxic shock syndrome is a fast progressing infection that causes shock and injury to internal organs, such as the kidneys, liver, and lungs. Over half of the patients with this syndrome die.

What are the early symptoms of necrotizing fasciitis and streptococcal toxic shock syndrome? Early symptoms of necrotizing fasciitis include fever, severe pain, swelling, and redness at the wound site. There are no symptoms specific only to streptococcal toxic shock syndrome, which makes it sometimes difficult to differentiate from other illnesses. The early symptoms may include fever, dizziness, confusion, diffuse flat red rash, and abdominal pain.

How are group A streptococci spread? They are spread by direct contact with secretions from the nose and throat of infected persons or by contact with infected wounds or sores on the skin. The risk of spreading the infection is highest when a person is ill, such as with strep throat or an infected wound. People who carry the bacteria, but have no symptoms, are much less contagious. Household items like plates, cups, pets, or toys probably do not play a major role in disease transmission.

Why does invasive group A streptococci disease occur? Invasive diseases, or infections, occur when the bacteria get past the defenses of the person who is infected. For example, the bacteria can get into the body through sores or other breaks in the skin like cuts, wounds, or chickenpox. Health conditions that decrease a person's immunity to infection also make invasive diseases more likely. In addition, certain strains of group A streptococci are more likely to cause severe disease than others.

How common is invasive group A streptococci disease? Approximately 10,000 to 15,000 cases occur in the United States each year, resulting in over 2,000 deaths. The Centers for Disease Control estimate that 500 to 1,500 cases of necrotizing fasciitis and 2,000 to 3,000 cases of streptococcal toxic shock syndrome occur each year.

Who is most at risk of getting invasive group A streptococci disease? Few people who come in contact with this highly infectious strain of bacteria will develop invasive disease. Many will have a routine throat or skin infection and most will have no symptoms at all. People with chronic illnesses like cancer, diabetes, AIDS/HIV, and kidney disease requiring dialysis and those who use medications such as steroids and chemotherapy are at higher risk than healthy people to develop an invasive disease.

How is group A streptococci disease treated? Many different antibiotics can treat group A streptococcal infections. Early treatment may reduce the risk of death in cases of invasive disease. It is always important to complete the entire course of antibiotics as prescribed. To avoid spreading the bacteria to others, stay home from work, school, or day care until 24 hours or more after taking an antibiotic.

What can be done to prevent group A streptococci disease? The spread of all types of group A streptococcal infections may be reduced by washing the hands with soap and water, especially after coughing and sneezing, before preparing foods, and before eating. Persons with sore throats should be seen by a doctor to rule out strep throat. Keep wounds clean and watch for possible signs of infection, increasing redness, swelling, drainage, and pain at the wound site. Seek medical care for signs of an infected wound, especially if fever develops.

Last Reviewed 2005

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIL File INFE4737.rf2 VRS# 4737 Data Version 7.0 Copyright 1998, 2003 McKesson Health Solutions LLC. All rights reserved.